JP2001317920A - Method and apparatus for measuring length of conveying material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable measurement of length with higher accuracy, regardless of difference in response speed between a photoelectric sensor and a CCD camera, even when the scanning cycle of the CCD camera is delayed. SOLUTION: A CCD camera 22 is made to scan a plurality number of times, before and after the detection timing of a photoelectric sensor 20, and the conveying speed of a conveying material 12 is computed from the image obtained and the period of the scanning. The time delay, until the detection of the position of the other end thereof with a CCD camera after the generation of a photoelectric sensor detection signal, is corrected using the resultant conveying speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring the length of a conveyed material.
Suitable for use when measuring by a combination of a CD camera, the position of one end of the transport material is detected by a photoelectric sensor, and the position of the other end of the transport material at the detection timing of the photoelectric sensor is imaged by a camera. The present invention relates to a method and an apparatus for measuring the length of a transport material for measuring the length of the transport material.

[0002]

2. Description of the Related Art As a device for measuring the length of a conveyed material, such as a hot steel material, which is conveyed at a high speed, conventionally,
(1) As described in JP-A-11-237214, a large number of photoelectric sensors are provided in the material transport direction, and the transport material is turned on / off by the leading and trailing ends of the transport material. How to measure the length of
(2) As described in JP-A-55-12478, a plurality of photoelectric sensors are provided on the upstream side of the conveyed material, and C is provided on the downstream side.
A method of providing a CD camera and measuring the length of a transported material from CCD camera information at the timing of detection signal output of a photoelectric sensor. (3) As described in JP-B-3-16602, the same television camera Calculate the moving distance from the detection of the front end position of the transfer material to the detection of the rear end position by integrating the movement speed detected by a separate speedometer to measure the length of the transfer material. Methods and the like are known.

[0003]

However, for example, in a line for transporting a plurality of hot steel materials, for example, the transport speed of the hot steel materials is 0 to 7 m / sec, and the measurement accuracy is guaranteed to be ± 1 mm in material length. There is a need for a length measuring device that can be used.

In such a line, when the length is measured by a combination of a large number of photoelectric sensors of the above (1),
In order to measure the length of all materials to be produced, a large number of sensors are required. In an actual production line, installation intervals are coarse because installation locations are limited, making it difficult to measure accurately. It is.

[0005] In order to solve such a problem, there is a method of providing a CCD camera downstream of the conveyed material and detecting the leading end as described in (2) above. At this time, in order to detect a material using a CCD camera, a transmission system in which a CCD camera is provided above the transport table and a light source is provided at a position opposite to the lower portion of the transport table is known. If this is attempted, it cannot be applied in many cases due to equipment restrictions such as being shielded from light by the transport rolls. Also, even if it can be installed, if the lower light source emits less light,
Maintenance must be performed at high frequency because measurement accuracy is affected. Further, even if maintenance is performed, the environment is poor and the work load is high.

For this reason, there is known a method of detecting a material by a self-luminous method utilizing light emission of a high-temperature material by heat. However, since the amount of self-emission greatly varies depending on the temperature of the material, the amount of light received by the CCD camera greatly changes,
For optimal high-precision detection of a CCD camera using an image sensor element, it is necessary to change the scanning cycle, exposure time, and aperture setting of the CCD camera. For example, a high-temperature material of 900 ° C. requires a high-speed scanning of 1 millisecond,
For low-temperature materials at 0 ° C, scan at a low speed of 5 ms,
It is necessary to increase the light receiving time and obtain the required light receiving amount.
There is a problem that a large deviation occurs in the detection cycle of the D camera, resulting in a large measurement error.

For example, as shown in FIG.
Assuming that the scanning cycle of the D camera is 5 milliseconds, when a detection signal of the photoelectric sensor comes in during the scanning time of (ii), (ii)
When the image information of the CCD camera i) is used, an error of the measurement timing of 4 ms occurs between the detection timing of the photoelectric sensor and the detection timing of the photoelectric sensor. If the conveying speed of the conveyed material is, for example, 7 m / sec, the measurement error of the material length is 4 × 7 = 28 mm, and when adding the response delay of the photoelectric sensor or the CCD camera to about 56 mm, the required accuracy cannot be satisfied. There was a problem that.

On the other hand, in the method (3) using a television camera and a speedometer described in Japanese Patent Publication No. 3-16602,
A separate speedometer is required, which not only complicates the configuration, but also has a problem that a speed measurement error directly leads to a length measurement error.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems.
It is an object to enable length measurement with high accuracy.

[0010]

According to the present invention, a position of one end of a conveyed material is detected by a photoelectric sensor, and a position of the other end of the conveyed material at a detection timing of the photoelectric sensor is imaged by a camera. In the method for measuring the length of a transporting material for measuring the length of the transporting material, the camera is scanned a plurality of times at least before and after the photoelectric sensor detection timing, and the transporting speed of the transporting material is calculated from the obtained image and its scanning cycle. Then, the problem is solved by using the length measurement.

In addition, a time delay from when the photoelectric sensor detection signal is generated to when the position of the other end is detected by the camera is corrected using the calculated transport speed.

According to another aspect of the present invention, there is provided a transport material length measuring apparatus, wherein a photoelectric sensor for detecting a position of one end of the transport material, and a position of the other end of the transport material at least before and after the detection timing of the photoelectric sensor. A camera that scans and captures a plurality of times, and a speed calculation unit that calculates a transport speed of the transport material from an image obtained by the camera and a scanning cycle thereof,
Using the transport speed calculated by the speed calculating means,
Correction means for correcting a time delay from when the photoelectric sensor detection signal is generated to when the other end position is detected by the camera, and using the end position data corrected by the correction means, By providing a length calculating means for calculating the length, the above-mentioned problem is also solved.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In this embodiment, as shown in FIG. 2, a photoelectric sensor for detecting the position of one end (here, a rear end 12b) of a conveyed material 10 being conveyed in the direction of arrow A by a conveying table 10 on the upstream side. 20 and at the downstream side, at least before and after the detection timing of the photoelectric sensor 20, the self-emission of the transport material 12 causes the other end (here, the tip 12
CCD camera 22 that scans the position of a) a plurality of times to take an image
And the detection signal of the photoelectric sensor 20 and the CCD camera 22
And a data analyzer 30 for calculating the length of the transport material 12 from the image data at each scan timing.

The data analyzer 30 is, for example,
A speed calculator 32 for calculating the transport speed of the transport material 12 from the image obtained by the CD camera 22 and the scanning cycle thereof.
And a correction unit 34 for correcting a time delay from when the photoelectric sensor detection signal is generated to when the tip position is detected by the CCD camera 22 using the transport speed calculated by the speed calculation unit 32. And a length calculation unit 36 for calculating the length of the transport material 12 using the end position data corrected by the correction unit 34.

Hereinafter, the operation of the present embodiment will be described. now,
Assuming that the detection signal of the photoelectric sensor 20 is transmitted within the scanning time (ii) shown in FIG. 3, the moving distance of the transport material 12 can be determined from the image data (i) to (iii) continuously measured at this time. , The scanning speed, the transport speed can be calculated.

Accordingly, errors due to the known response delay of the photoelectric sensor 20 and the processing delay of the CCD camera 22 are corrected based on the transport speed, and the detection timing of the photoelectric sensor 20 and the detection timing of the CCD camera 22 are synchronized. The accurate detection timing of the photoelectric sensor 20 within the scanning time (ii) can be found. From this data and the speed data of the material, it is possible to know the accurate position of the material tip when the photoelectric sensor is detected, and to measure the length of the material from the relationship between the position of the photoelectric sensor 20 and the CCD camera 22 and the tip detection information. can do.

[0018]

The scanning cycle of the CCD camera 22 may be 0.5 millisecond when the material temperature is as high as about 900 ° C.
At a low temperature of about 600 ° C., a clear image cannot be obtained unless about 5 milliseconds. Therefore, when the scanning cycle of the CCD camera 22 is set to 5 milliseconds and the moving distance of the material in the scanning cycles (i) to (iii) is 105 mm as shown in FIG. 3, the transport speed is 7 m / sec. Becomes At this time, if the response delay of the photoelectric sensor 20 is 1 millisecond and the processing delay of the CCD camera 22 is 1 millisecond, it can be seen that there is a measurement delay of 7 mm each.

Therefore, when a detection signal of the photoelectric sensor 20 is received within the scanning time of (ii) (for example, 3 milliseconds after the start of scanning), the tip position at that time is determined by the scanning period (ii)
7 × 3 = 21 m with respect to the detection position (solid line B in FIG. 3)
It can be seen that this is a position that has advanced to m downstream.

Therefore, the actual tip position (broken line C in FIG. 3) can be determined from the response delay amount of the photoelectric sensor 20 and the CCD camera 22 and the CCD camera detection position correction at the photoelectric sensor detection timing based on the transport speed. Therefore, the length of the transport material 12 can be measured from the positional relationship between the corrected tip detection position C and the known photoelectric sensor 20 and CCD camera 22.

In the above description, the photoelectric sensor 2
0, the rear end 12b of the transport material 12 is detected, and the front end 12a of the transport material 12 is detected by the CCD camera 22. However, the arrangement of the photoelectric sensor and the CCD camera is reversed, and the transport by the photoelectric sensor 20 is performed. Tip 1 of material 12
It is apparent that the present invention can be similarly applied to the case where the length is measured from the position of the rear end 12b of the conveyed material 12 detected by the CCD camera 22 when 2a is detected.

The present invention is suitable for detecting a low-temperature material having a small amount of self-emission with a CCD camera, but the present invention is not limited to this, and the present invention is not limited to this. It is clear that the present invention can be similarly applied to the case of measuring a general transport material.

[0023]

According to the present invention, even when the scanning cycle of the camera is slow, the influence of the difference in the detection time caused by the difference in the response speed between the photoelectric sensor and the camera is eliminated, and the length of the conveyed material can be adjusted accurately. It becomes possible to measure well.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a relationship between a detection signal of a photoelectric sensor, a scanning timing of a CCD camera, and image information for explaining a conventional problem.

FIG. 2 is a diagram showing an overall configuration of an embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of a relationship among a detection signal of a photoelectric sensor, a scanning timing of a CCD camera, and image information for explaining the operation of the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Convey table 12 ... Convey material 12a ... Top 12b ... Rear end 20 ... Photoelectric sensor 22 ... CCD camera 30 ... Data analyzer 32 ... Speed calculation circuit 34 ... Correction circuit 36 ... Length calculation circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 AA07 AA12 AA22 BB13 CC06 DD03 EE00 EE03 FF04 FF26 FF32 FF34 JJ01 JJ03 JJ18 JJ26 MM03 MM22 MM28 PP01 PP16 QQ13 UU02 UU05 4K034 AA19 DB08

Claims (3)

[Claims] 1. A transfer material for detecting the position of one end of the transfer material by a photoelectric sensor, capturing the position of the other end of the transfer material at a detection timing of the photoelectric sensor by a camera, and measuring the length of the transfer material. In the length measuring method, at least before and after the photoelectric sensor detection timing, the camera is scanned a plurality of times, the transport speed of the transport material is calculated from the obtained image and its scanning cycle, and the length measurement is performed. A method for measuring the length of a transport material, which is used. 2. A time delay from when the photoelectric sensor detection signal is generated to when the other end position is detected by the camera is corrected using the calculated transport speed. 2. The method for measuring the length of a transport material according to 1. 3. A photoelectric sensor for detecting a position of one end of a conveyed material, a camera for scanning and imaging a position of the other end of the conveyed material a plurality of times at least before and after the detection timing of the photoelectric sensor, From the obtained image and the scanning cycle thereof, a speed calculating means for calculating a conveying speed of the conveyed material, using the conveying speed calculated by the speed calculating means,
Correction means for correcting a time delay from when the photoelectric sensor detection signal is generated to when the other end position is detected by the camera, using the end position data corrected by the correction means, A length measuring device, comprising: a length calculating means for calculating a length;